I have 3 solutions for you:
Solution 1: <details> and <summary>
In your example you should probably use the <details> and <summary> elements:
label {
display: block;
}<fieldset disabled>
<legend>
Personalia:
</legend>
<label>Name: <input></label>
<label>Email: <input></label>
<label>Date of birth: <input></label>
<label>Somethingelse: <input></label>
<details>
<summary>View Details</summary>
<p>A more detailed description</p>
</details>
</fieldset>Solution 2: Put your button inside the <legend>
If your are not disclosing a more detailed information, but you want to, say, toggle the disabling of the fieldset, then you can put the toggle button in the <legend> element
const fieldset = document.querySelector("fieldset");
const toggleButton = document.getElementById("toggle-button");
toggleButton.addEventListener("click", (event) => {
fieldset.disabled = !fieldset.disabled;
toggleButton.textContent = fieldset.disabled ? "Enable" : "Disable";
toggleButton.setAttribute("aria-pressed", `${!fieldset.disabled}`);
});label {
display: block;
}<fieldset disabled>
<legend>
Personalia:
<button id="toggle-button" aria-pressed="true">
Enable
</button>
</legend>
<label>Name: <input></label>
<label>Email: <input></label>
<label>Date of birth: <input></label>
<label>Somethingelse: <input></label>
<button>This may be disabled</button>
</fieldset>Solution 3: Use a “fake” button
If your use-case is something entirely different, you can use aria-roles to “fake” a button role="button" (see ARIA button role). Remember to add the necessary accessibility features to make this button clickable for users without display screens or mouse. The important attributes are role="button" (for screen readers) and tabindex="0" (for keyboard navigation), also remember to add a handler for keypress for Enter and Space in case your user doesn’t have a mouse.
const disabledButton = document.querySelector('.disabled-button');
const disabledOutput = document.querySelector('.disabled-output');
const enabledButton = document.querySelector('.enabled-button');
const enabledOutput = document.querySelector('.enabled-output');
function increment(output) {
const current = Number.parseInt(output.textContent);
output.textContent = `${current + 1}`;
}
disabledButton.addEventListener('click', () => increment(disabledOutput));
disabledButton.addEventListener('keypress', event => {
if (['Enter', ' '].includes(event.key)) {
increment(disabledOutput);
}
});
enabledButton.addEventListener('click', () => increment(enabledOutput));
enabledButton.addEventListener('keypress', event => {
if (['Enter', ' '].includes(event.key)) {
increment(enabledOutput);
}
});label {
display: block;
}
[role="button"] {
-webkit-appearance: button;
appearance: button;
cursor: default;
font-style: normal;
-webkit-user-select: none;
user-select: none;
}<fieldset disabled>
<legend>Disabled form elements</legend>
<label>Input 1<input name="input 1"></label>
<label>Input 2<input name="input 2"></label>
<button
class="disabled-button"
name="disabled-button"
>
This is disabled
</button>
<i
class="enabled-button"
role="button"
tabindex="0"
>
This is enabled
</i>
</fieldset>
<label>
Disabled button clicks:
<output class="disabled-output">0</output>
</label>
<label>
Enabled button clicks:
<output class="enabled-output">0</output>
</label>